Regulation of hormones Flashcards
how are hormones regulated
most are regulated by a reflex pathway;
stimulus > afferent signal > integration > efferent signal (hormone) > physiological action > negative feedback some have multiple stimulus or multiple feedback loops
what does the endocrine cell act as
the sensor, determines whether the hormone needs to be released or stop being released
what are the three major groups of neurohormones
catecholamines (produced in the adrenal medulla)
hypothalamic produced in anterior and posterior pituitary
what hormones are produced in the posterior pituitary
vasopressin - anti-diuretic hormone, regulation of water balance
oxytocin - produced during uterine contractions, after birth it stimulates ejection of breast milk
what hormones are produced in the anterior pituitary
prolactin
thyrotropin (thyroid stimulating hormone)
adrenocorticotropin (ACTH)
growth hormone
follicle stimulating hormone and lutenising hormone
what is secretion of all anterior pituitary hormones contolled by
hypothalamic neurohormones
what is a trophic hormone
a hormone that controls the secretion of another hormones
hypothalamic hormones are trophic hormones but they are called releasing or inhibiting hormones
what are the three levels of endocrine control
hypothalamic stimulation from CNS
pituitary stimulation from hypothalamic trophic hormones
endocrine gland stimulation from pituitary trophic hormones
what is long-loop feedback
hormone released from final target cell feeds back to supress anterior pituitary and hypothalamic hormones
what is short-loop feedback
pituitary hormones feed back to supress hypothalamic hormones
what does negative feedback allow
allows hormones to stay withing range
what is the function of the hypothalamic-hypophyseal portal system
hypothalamic trophic hormones are transported to pituitary through the hypothalamic-hypophyseal portal system
allows for a small amount of hormone to elicit a given response
what is a portal system
a specialised region of the circulation consisting of two sets of capillaries directly connected by a set of blood vessels
what are the advantages of a portal system
less dilution of hormone
smaller amount of hormone is used to elicit a certain response
delivered directly to target
only a small number of neurosecretory neurons in the hypothalamus can effectively control activity of anterior pituitary
